<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <style>
    table {
      margin: 0 auto;
      margin-top: 30px;
      border-collapse: collapse;
    }

    td {
      width: 30px;
      height: 30px;
      text-align: center;
    }
  </style>

  <body>
    <table border="1">
      <tr>
        <td colspan="12">1</td>
        <td rowspan="12">2</td>
      </tr>
      <tr>
        <td rowspan="12">4</td>
        <td colspan="10">5</td>
        <td rowspan="10">6</td>
      </tr>
      <tr>
        <td rowspan="10">8</td>
        <td colspan="8">9</td>
        <td rowspan="8">10</td>
      </tr>
      <tr>
        <td rowspan="8">12</td>
        <td colspan="6">13</td>
        <td rowspan="6">14</td>
      </tr>
      <tr>
        <td rowspan="6">16</td>
        <td colspan="4">17</td>
        <td rowspan="4">18</td>
      </tr>
      <tr>
        <td rowspan="4">20</td>
        <td colspan="2">21</td>
        <td rowspan="2">22</td>
      </tr>
      <tr>
        <td rowspan="2">24</td>
        <td>25</td>
      </tr>
      <tr>
        <td colspan="2">23</td>
      </tr>
      <tr>
        <td colspan="4">19</td>
      </tr>
      <tr>
        <td colspan="6">15</td>
      </tr>
      <tr>
        <td colspan="8">11</td>
      </tr>
      <tr>
        <td colspan="10">7</td>
      </tr>
      <tr>
        <td colspan="12">3</td>
      </tr>
    </table>
  </body>
</html>
